March 4, 2009

Scientists from Australia's CSIRO Plant Industry and international collaborators have discovered the key to overcome three major cereal diseases that have cost wheat producers worldwide in excess of A$7.8 billion (US$4.9 billion).

Scientists have identified a wheat gene sequence that provides protection against leaf rust, stripe rust and powdery mildew.

Genetic disease resistance is highly desirable in plants as it is more environmentally friendly and profitable than strategies such as spraying pesticides, said senior principal research scientist at CSIRO Plant Industry, Dr Evans Lagudah.

The newly identified gene sequence - known as Lr34 transporter protein - is the first of its kind to be found in a commercial crop that is capable of delivering broad-spectrum control of multiple pathogens, Lagudah said.

Lr34 not only could provide long-lasting disease resistance, but it also acts against multiple diseases.

Fungi that cause rust diseases are very adaptable and can rapidly evolve to overcome resistant grain varieties, and scientists and farmers could normally only respond to a rust outbreak after it has passed, Lagudah said.

However, tests found that the Lr34 gene sequence has provided partial but constant protection against leaf rust for over 80 years, Lagudah said.

Understanding the molecular nature of this type of resistance is important for the long-term control of rust diseases.

CSIRO's Dr Wolfgang Spielmeyer said an immediate application is the use of the gene sequence to directly select and breed wheat plants that carry that resistance against multiple pathogens.

The Lr43 gene can now be combined with other disease resistance genes into single cultivars faster, providing a more durable resistance, Spielmeyer said.